Flexible shaft hand tool



Nov. 26, 1957 w. J. KUPFRIAAN FLEXIBLE SHAFT HAND TOOL Filed Jan."6.1955 INVENTOR.

FLEXIBLE SHAFT HAND TOOL Wilbur I. Kupfrian, Binghamton, N. Y., assignorto Kupfrian Manufacturing Corp.

Application January 6, 1955, Serial No. 480,157

3 Claims. (Cl. 14561) This invention relates to hand tools and moreparticularly to a screw or nut driver having a flexible shaft memberextending between the handle and the tool bit. Tools of this type havebeen in general use for some time, but have not been completelysuccessful because they lacked certain details essential to good tradeperformance.

The principal object of the present invention is to provide an improvedflexible shaft hand tool that overcomes many of the defects found inearlier structures; to provide a flexible shaft type screwdriver orsimilar tool having improved means for journalling the casing to theflexible shaft at both ends; to provide an improved flexible shaft typescrewdriver having an improved means for securing the flexible shaftwithin the handle; to provide an improved flexible shaft tool having abit portion, a handle portion, and a flexible shaft connection betweenthe two with a covering extending between the bit and the handle thatprovides complete electrical insulation along its entire length; toprovide improved means for interchanging bits, and for providingsuitable thrust for the bits. These and other objects will become moreapparent from the drawing and from the accompanying description.

In the drawing:

Fig. 1 is an elevational view of one form of the invention, showing thetwo ends disposed at 90 from the normal aligned position.

Fig. 2 is a partial sectional view taken on the line 2-2 of Fig. 1.

Fig. 3 is a sectional view of the bit end of the tool taken on the line3-3 of Fig. 1; and

Fig. 4 is a view similar to Fig. 3 showing a modified tip constructionallowing for interchangeability of bits.

Referring again to the drawing, the improved tool T is shown as ascrewdriver for convenience in illustrating and describing theinvention, though it will be understood that the principles of theinvention are applicable to other similar tools, such as tap holders,reamers, nut setters, and the like. As shown, the tool comprises ahandle and a tool bit 11 such as a screwdriver bit or other tool elementas previously described. The handle and bit are operatively connected bymeans of a flexible shaft 12 of conventional design, and preferablyconsisting of a single center wire upon which successive layers of wiresare wrapped, each layer being wound in a direction opposite from that ofthe preceding layer. I prefer to employ flexible shafting known in thetrade as remote-control flexible shafting which exhibits similarstrength characteristics in either direction of operation. Such shaftingemploys more Wires per layer, and smaller diameters of wire than arefound in other types. The shaft should employ steel wires in itsconstruction, though for nonmagnetic or non-corrosive properties, othermaterials such as bronze or nickel-containing alloys may be used. Thesize of the shaft is selected so as to be capable of imparting the fulltorque load that ordinarily can be imparted to the handle 10 when it isgripped in the hand. Although this load varies according to the diameterof tired tates Paten Patented Nov. 26, 1957 proximately A in diameter atorque of approximately 25 lb. in. is satisfactory, and flexible shaftsmeeting this load requirement are obtainable in diameter size.

Most shafts of the remote-control type are wound under an essentialinitial tension, which tends to cause the layers to unravel when outunless special precautions are taken. I prefer to deform the shaft intopolygonal crosssection in the region of the cutting zone, so that itsafely may be severed in the deformed region. The shaft is attached inany convenient manner to the handle 10 and to, the tool bit 11, thoughpreferred methods are illustrated in Figs. 2 and 3. The connection tothe handle preferably is made by means of a terminal or tubule 13 whichinitially may be passed freely over the end of the flexible shaft 12,following which the end portion may be deformed from the roundcross-section to form a polygonal shaped section 14 for keying the shaftwithin the handle. By forming the section 14 with the same number ofsides as the deformed section on the flexible shaft, a better bondbetween the parts is obtained. The deformed end of the flexible shaftotherwise may be inserted directly within the handle 10, but the tubule13 offers advantages in that it strengthens the shaft at the point ofconnection within the handle, and at the same time provides aninflexible cylindrical portion 15 adjoining the handle that ,may bejournalled within a ferrule 16 and within the casing 19 as will be morefully described.

The terminal 13 may be imbedded within the handle- 10 in anyconventional manner. If the handle consists of wood, the parts may becemented together. I prefer,

however, to use a plastic handle in which case the terminal 13 may bemolded directly within the handle at the time the handle is formed, orit may be inserted later. I prefer to use avpreformed thermoplastichandle having a cavity 17 to receive the deformed section 14. Cement ora press fit may be used, though I prefer to heat the deformed section14, so that it softens the plastic material, forms longitudinal groovestherein corresponding with the shape of the deformed section, andautomatically cements itself to the thermoplastic material. Experiencehas shown that the cavity 17 should have a diameter slightly greaterthan the distance across flats on the deformed section 14 to accommodatethe normal flow of softened material, and to allow for the adequateescape of entrapped air.

At the opposite end, the flexible shaft 12 is secured to the tool 11,preferably by crimping it within a cavity formed directly in the tip. Asbefore, the resulting crimped portion 18 preferably is of polygonalcrosssection, of a shape corresponding with the crimp previouslyimparted to the shaft 12 at the end region. The crimped portion on thetip preferably starts at a point spaced from the opening of the cavity,whereby the wall portion forming the opening to the cavity retains itsoriginal circular shape to provide a better bearing surface as willappear, and to avoid weakening the edges of the aperture.

The region between the handle 10 and the bit 11, surrounding theflexible shaft, is enclosed within a suitable casing 19 whichcontributes substantially to the capacity of the tool, lessensobjectionable buckling tendencies under heavy load conditions, andprotects the flexible shaft 12 from injury, corrosion, and from loss ofsurface lubricant. I prefer to use a casing that bends substantiallyabout a neutral axis to minimize changes in length when the easing arcs.For this purpose I prefer a casing composed of a liner member 21preferably employing spring wire of rectangular cross-section, formedinto spaced turns as illustrated in Fig. 3. When casing of this typebends in an arc, the turns on the inside radius tend to compress, andthe turns on the outer radius tend to expand, resulting in little or nooverall change in length. The casing liner 21 preferably is enclosedwithin a flexible cover 22, typically a tube of rubber, or plasticizedthermoplastic, such as vinyl or ethylene compounds. This coveringeffectively closes the turns in the liner member, making a leak-proofenclosure, and also electrically insulates the enclosed metallic partsfrom contact with electrically charged members.

A handpiece or journal member 23 is provided adjacent to the tool bit11, and is provided with a bore 24 for rotatively receiving a spindleportion 25 of the bit 11. The handpiece 23 is relieved at one end with alarger diameter portion 27 for receiving the forward end of the casing19. A thrust collar 26 comprising a shoulder on the spindle 25, or aretaining ring as shown in Fig. 3, is employed to impart end thrust tothe tool bit 11. For the handpiece 23, I prefer to use a plastic tubeformed of an extruded thermoplastic, or a wrapped phenolic tubereinforced with paper or fabric. The latter is available under varioustrade names and finds frequent application where high strength andwear-resistance are desirable. In any event, both the handpiece 23 andthe ferrule 16 are made of electrically insulating materials, so thatthe entire structure from the handle to the tip is completely enclosedand electrically insulated. The ferrule 16 may be relieved with anenlarged diameter portion 28 as was employed on the handpiece 23, andthe casing may be inserted freely within the enlarged diameter portion,or may be secured within the opening in any suitable manner, as bycementing.

The handpiece and tip construction shown in Fig. 4 differs from Fig. 3primarily in that the spindle 25 is made hollow at its forward end,having an inside diameter suitable for receiving interchangeable bits29. Any conventional collet or chuck 30 may be employed, though forpurposes of illustration I show the spindle 25 provided with an enlargedportion threaded to receive nut 31. The threaded portion also may beprovided with diametrally opposed slots 32 for slidable engagement withcooperating members such as lugs or ears 33 formed in the bit 29. Thenut 31 and the threaded portion may have cooperating conical faces asindicated at 34 operative when the nut 31 is tightened to constrict thehalves of the collet 30 locking the bit 29 in position. As analternative, the nut and/ or the threaded spindle may employ taperthreads causing a similar constricting action when the parts are fullymated. The slopnig conical faces 34 are to be preferred because theyallow a more exact positioning of the nut 31 in the fully engagedposition. This is particularly important where I may prefer to locatethe rear face 35 of the nut directly adjacent to the forward wall of thehandpiece 23 to operate as a thrust collar as shown in Fig. 4. Asillustrated also in Fig. 4, the

threads on the spindle 25 may be relieved adjacent to the rear part ofthe nut, and the nut wall may be crimped inwardly after assembly topreclude subsequent removal and possible accidental loss of the nut fromthe spindle 25.

Although I have shown several variant forms of the invention toillustrate the novel principles, it is to be understood that I do notwish to limit myself by the disclosure of the drawings, as I contemplateany structure properly within the scope of the appended claims.

I claim:

1. A hand tool comprising a tool chuck, a handle, a

' flexible shaft extending between said chuck and said handle, a casingfor said flexible shaft, ferrules on said casing at each end thereof,and a tubular member surrounding a terminal portion of said flexibleshaft and projecting within said handle, at least a part of said memberand said terminal portion being deformed to preclude relative motionbetween them, said tubular member being fixed within said handle.

2. A hand tool comprising a tool support, a handle, a flexible shaftconnected to said support and projecting within said handle, a casingfor said flexible shaft, and a tubular member encircling the handle endof said flexible shaft, said member being deformed so as to anchor saidshaft within said member, said member in turn being anchored within saidhandle.

3. A hand tool comprising a tool chuck, a handle, a flexible shaftextending between said chuck and said handle, a casing for said flexibleshaft, ferrules on said casing at each end thereof, and a tubular membersurrounding a terminal portion of said flexible shaft and projecting atone end within the end of said casing nearest said handle, said memberbeing secured to said terminal portion of said flexible shaft, saidtubular member also extending within said handle and being securelyattached thereto.

References Cited in the file of this patent UNITED STATES PATENTS871,155 Wood Nov. 19, 1907 1,225,249 Holtschneider May 8, 1917 1,343,101Weaver June 8, 1920 1,507,990 Donaldson Sept. 9, 1924 1,624,530 CarusoApr. 12, 1927 1,902,438 Foley Mar. 21, 1933 1,903,660 Smith et al Apr.11, 1933 1,999,051 Kennedy Apr. 23, 1935 2,023,693 Miller Dec. 10, 19352,619,860 Gray Dec. 2, 1952 FOREIGN PATENTS 605,130 Great Britain July16, 1948

